The present invention relates to a device for rendering contactors mechanically and electrically inoperative, in which the original design of the mobile elements makes it possible to obtain an arrangement of the output terminals which facilitates wiring and interchangeability with existing systems providing mechanical inoperativeness.
1. Field of the Invention
It is generally known that devices of this kind providing such inoperativeness are usually associated with contactors for controlling electric motors so as to prevent simultaneous switching on and so short-circuiting particularly when these contactors provide reversal of operation and star-triangle starting.
Such inoperativeness may be electric alone, however, in order to prevent operating errors, it is preferable for it to be both electric and mechanical.
The provision of electric inoperativeness between two contactors consists in actuating, in the first third of the travel of the closing contactor, but preferably as early as possible, a contact which opens the circuit of the coil of the other contactor and vice-versa.
Mechanical inoperativeness uses a system of levers which are interlocked so that when one contactor has begun to close, it is impossible to close the other.
In automatic operation, electric inoperativeness alone would be sufficient. However, in the case of the simultaneous energization of two contactor coils, or in the case of a shock causing the movement of their mobile assemblies, or else in the case of wrong actuation of these contactors, there is a risk of short-circuiting by the simultaneous closure of the power poles of both contactors. This is why mechanical inoperativeness is generally associated with electric inoperativeness.
2. Description of the Prior Art
To provide such mechanical inoperativeness, even in the case of contactors mounted side by side, a locking mechanism is generally used incorporated in a case from which project movement take-off fingers. This case is then placed between two contactors so that the movement takeoff fingers are coupled respectively with actuation members provided in said contactors.
The electric inoperativeness is generally provided by using one of the break contacts (or NC as they are generally called) usually provided on each of the contactors, it being understood that this solution has the drawback of reducing the number of contacts available on each contactor.
To overcome this drawback, a device has been proposed in the form of a module adapted for fitting between the two contactors to be locked and comprising both levers providing mechanical inoperativeness and contacts providing electric inoperativeness. A device of this kind which provides simultaneously mechanical and electric inoperativeness is described in the French patent issued to the firm UNELEC, No. 2 045 090 on May, 30, 1969.
Another more recent and more compact device which can be used between two contactors is described in the PCT patent to ALLEN BRADLEY COMPANY (USA) No. 85 03382 dated Jan. 23, 1984.
It can however be observed that the embodiments proposed in this patent have the drawback that the input and output terminals assigned to one of the contacts are placed on the same side of the case of the device whereas the input and output terminals of the other contact are placed on the other side of this case. This feature, which results from the general design of the device, is particularly troublesome, not only in so far as safety and the simplicity of providing interconnecting wiring are concerned, but also the risks of error which this arrangement may give rise to.
The purpose of the invention is particularly to overcome these drawbacks.